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QUESTION-TYPE BASED TESTS
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TEST 7 – Saving the British Bitterns
A.
Breeding bitterns became extinct in the UK by 1886 but, following recolonization early last
century, numbers rose to a peak of about 70 booming (singing) males in the 1950s, falling to fewer than 20
by the 1990s. In the late 1980s it was clear that
the bittern was in trouble, but there was little information on
which to base recovery actions.
B.
Bitterns have cryptic plumage and a shy nature, usually remaining hidden within the cover of reed
bed vegetation. Our first challenge was to develop standard methods to monitor their numbers. The boom of
the male bittern is its most distinctive feature during
the breeding season, and we developed a method to
count them using the sound patterns unique to each individual. This not only allows us to be much more
certain of the number of booming males in the UK, but also enables us to estimate local survival of males
from one year to the next
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